Did you know that your thoughts create your reality, that is, the situations around you? Did you know that what you think is what will happen? The darker the thoughts, the darker the incidents in one's life.
Many experiments have been done around the power of belief. The best known example is how scientists can influence the outcome of experiments that they are doing. When the outcome is as they expected, the events in the experiment become a "self fulfilling prophecy". In other words, what they believed they would get are the results that showed up. More fascinating is that scientists that did the same experiment and had a different belief around the outcome, did get different results than the first group of scientists. This has spawned the saying, "What you believe is what you get."
Thought is communication with one's self. How do you change it? How do you move past your current belief system? There are many self help tools out in the world that can help you with this change. The big factor in any change is that you must want to do a change.
The question now is, "What do you believe to be true about yourself, and how is that working for you?"